import pandas as pd
s2 =pd.Series([10,20.30],index=['a','b','c'])
print(s2)
print(s2['a'])
print(s2[0])
print(s2['a':'c'])
print(s2[0:2])

s2['a']=100
s2['d']=200
print(s2.sum())
print(s2.mean())
print(s2.median())